HP Veritas Volume Manager 5.0 -UX 11i v3 manual Provide redundant loop access, C2t99d0

Understanding Veritas Volume Manager

How VxVM handles storage management

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In High Availability (HA) configurations, redundant-loop access to storage can be implemented by connecting independent controllers on the host to separate hubs with independent paths to the enclosures as shown in Figure 1-4.

Figure 1-4	Example HA configuration using multiple hubs or switches to
	provide redundant loop access

c1 c2

Host

enc0enc1

enc2

Fibre Channel hubs or switches

Disk enclosures

Such a configuration protects against the failure of one of the host controllers (c1 and c2), or of the cable between the host and one of the hubs. In this example, each disk is known by the same name to VxVM for all of the paths over which it can be accessed. For example, the disk device enc0_0 represents a single disk for which two different paths are known, such as c1t99d0 and

c2t99d0.

Note: The native multipathing feature of HP-UX 11i v3 similarly maps the various physical paths to a disk, and presents these as a single persistent device with a name of the form disk##. However, this mechanism is independent of that used by VxVM. For instructions on administering native multipathing with Base-VxVMand VxVM-Full, please consult the Release Notes for VxVM 5.0 on 11i v3.

To take account of fault domains when configuring data redundancy, you can control how mirrored volumes are laid out across enclosures as described in “Mirroring across targets, controllers or enclosures” on page 255.